1. Field of the Invention
The present invention relates to a packaging box and the method of packaging and more specifically to a packaging box which can easily be opened and the method of assembling the packaging box.
2. Description of the Prior Art
In the process of making a packaging box and of packing and sealing a product or article in it, a paper board is formed into a square cylinder; the product is inserted in it; inner flaps 10, 11, 12, 13, bonding flaps 8, 9 and end sections 6, 7 are folded in that order; and the bonding flaps 8, 9 and the end sections 6, 7 are joined to seal the product. As an example of the conventional method of making the packaging box with a feature that allows easy opening of the box for extracting the contents and which permits information printing on the inner surface, the Japanese Utility Model Laid-Open No. 1982 and No. 89/1984 may be cited. That is, a perforated line is cut along the folding line 14 on one side of the end section or on that part of the end section near the folding line but not adjoining the bonding flap 8 or 9 to make easy the opening of only the end section of the box together with the bonding flap joined to it. Another example is the one in which the perforated line is cut extending from one corner of a particular side wall section 1, 2, 3 or 4, toward the opposing corner without passing the folding line. Or the perforation starts at the external side of one of the inner flaps, passes through the side wall section adjoining the inner flap and reaches the external side of the other inner flap that opposes the first inner flap. In this example, the box is easily opened for extracting the contents by breaking the side wall section along the perforated line and lifting it toward the other side wall section.
The problem of these conventional arts is that when perforation is cut on the folding line of one of the end sections or near the folding line, the inner flap cannot be lifted. Because of this drawback, this method is not so effective in facilitating the opening of the box.
Another disadvantage is that since the perforation is cut in only one of the end sections, the opposing end sections have unequal folding strengths and thicknesses. As a result, in the packaging process of inserting and sealing an article in the box, i.e., when many stacked two-folded flat boards are successively taken out one at a time and formed into a square cylinder, troubles occur such as failures to extract boards correctly or form the boards into the correct shape, thus deteriorating the efficiency of the packaging process.
There is a further drawback. When the perforation is cut through a particular side wall section, the length of the perforation is longer than at least one of the sides of the box. In that case when it is attempted to open the box, the breaking of perforation will not propagate continuously to those remote parts of the perforation away from the force application point and may deviate from the perforation into other parts of the side wall section.
Therefore, it is necessary to avoid printing information on the inside of the side wall section through which the perforation passes and this reduces the effective area available for printing.